138 UPPER CRETACEOUS-LOWER TERTIARY FORAMINIFERA 



i. Chambers on the dorsal side, 15 to 18, arranged in three dextrally coiled 



whorls (all the studied specimens coiled dextrally). 

 2. Chambers in the last whorl, 5-6, compared with 5-9 in the specimens studied 



by Dalbiez. 



Remarks. Dalbiez (1955 : 169) described G. stuarti stuartiformis as a subspecies 

 of G. elevata (Brotzen) and named it G. elevata stuartiformis. He considered G. 

 stuarti of Papp & Kiipper (1953 : 39, pi. 2, figs, la-c), which appears to be G. 

 elevata (Brotzen), as synonymous with the present subspecies. Both Dalbiez and 

 Berggren (1962) considered the single keeled form, wrongly described as G. area by 

 Cushman (1946 ; pi. 62, figs. $a-c), as belonging to this subspecies although it lacks 

 the characteristic triangular last chambers and the straight angular sutures on the 

 dorsal side. However, Dalbiez's subspecies is actually more closely related to the 

 G. stuarti group than to G. elevata Brotzen as it differs from the latter in the form of 

 the test, the shape of the chambers both on the dorsal and the ventral sides, and in 

 the form of the sutures on both sides. 



Pessagno (i960 : 101) followed by Berggren (1962 : 62, 63), realizing this, made 

 G. elevata stuartiformis Dalbiez a subspecies of G. stuarti (de Lapparent) and changed 

 its name to G. stuarti stuartiformis Dalbiez. These authors then went to the other 

 extreme and considered G. elevata (Brotzen) as another subspecies of G. stuarti 

 (de Lapparent) and changed its name to G. stuarti elevata (Brotzen). However, 

 although Glaessner (1937 : 39) considered G. elevata (Brotzen) as synonymous with 

 G. stuarti (de Lapparent), and Papp & Kiipper (1953 : 39, pi. 2, figs. 2a-c) apparently 

 misidentified G. elevata for G. stuarti, it has to be mentioned here that G. elevata 

 is both morphologically and stratigraphically different from G. stuarti and thus 

 should be kept separate and should retain its original name, G. elevata (Brotzen). 



Dalbiez (1955 : 164) suggested that G. stuarti stuartiformis had evolved into 

 G. stuarti stuarti (de Lapparent) during Upper Campanian time by the development 

 of a biconvex test and by the change of the triangular chambers on the dorsal side 

 into the characteristic trapezoidal form. However, it seems more probable that 

 G. stuarti stuartiformis has evolved into G. stuarti subspinosa during Campanian time 

 and that the latter, in its turn, evolved into G. stuarti stuarti. The stratigraphical 

 ranges and the diagnostic features of each of these subspecies support this proposition. 



Specimens of G. stuarti stuartiformis (Dalbiez) from the Esna-Idfu region conform 

 well with the holotype of Dalbiez and with topotypes kindly forwarded by him to the 

 present author, although they are slightly smaller. 



Hypotype. P.45558. 



Horizon and locality. Figured specimen, from sample No. 18, W. El- 

 Sharawna section. 



Stratigraphical range. Dalbiez (1955 : 167, 169, chart 2) recorded the 

 approximate range of G. stuarti stuartiformis in northeastern Tunisia as Campanian- 

 Lower Maestrichtian, and added that " many specimens identified as G. stuarti from 

 the Upper Santonian and Campanian undoubtedly belong to the present subspecies ". 



Subbotina (1953 : 201, pi. 15, figs. Z a ~5 c ) described as G. stuarti de (Lapparent) 



